The translation is basically right. :) That medal was apparently issued in 1861 when the city of Braunschweig/Brunswick had its millennium celebration. "Auch fortan mit Rosses- und Löwenkraft vorwärts" refers to the lion - symbol of Braunschweig - and the horse which was the symbol of the duchy of Braunschweig-Wolfenbüttel. Even today the city of Braunschweig has the lion in its CoA while the state it is in (Lower Saxony) has the horse.
The other side ("Seit tausend Jahren" - "Jubeljahr 1861") suggests that the city of Braunschweig was founded in 861. And indeed that was what they celebrated in 1861, with a big three-day party in August. Except that the city is most probably not that old: What we know today suggests that the city came into being around the year 1030. (In other words, time to prepare for the next millennium party, hehe.)
Here is another "Millennium" medal (just one side). The year at the end may look like 1981 but is 1861 of course:
http://de.wikipedia.org/w/index.php...Brunonia.jpgChristian